Polymers of vinyl alkyl ethers



States POLYNIERS OF VINYL ALKYL ETHERS No Drawing. Application September8, 1950, Serial No. 183,919

5 Claims. (Cl. 260=-91.1)

This invention relates to resilient rubber-like polymers of vinyl alkylethers.

This application is a continuation-in-part of my prior applicationsSerial No. 587,838 and Serial No. 587,839, filed April 11, 1945, andSerial No. 681,129, filed July 2, 1946.

Polymerization of vinyl ethers by means of acid-reacting catalysts hasbeen described heretofore, for example, in U. S. P. 2,061,934, U. S. P.2,098,108, U. S. P. 2,104,000, U. S. P. 2,104,001, U. S. P. 2,104,002and U. S. P. 2,188,778, French Patent 734,129, Chalmers Canadian Journalof Research, vol. VII (1932), pages 472-480, and Shostakovskii et 21.Chemical Abstracts 37 (1943), page 2486.

It is one of the major aims of workers in the polymerization field toproduce high molecular products which are form-stable. By form-stable, Imean products which, under ordinary conditions, retain their shape onstanding and do not flow to take the form of the vessel in which theyare confined. The reason for the desire to obtain the form-stablepolymers is due to the fact that such polymers may be put toapplications for which the non-form-stable products are unsuitable. Theymay, for example, be used in the molding, pressure-casting and extrusionart. They may be rolled out into thin sheets for use in lamination workor for use as wrapper films, container coatings and the like. They mayalso be used as electrical and heat insulators depending upon theelectrical characteristics and softening point thereof. They may also beemployed in many cases as rubber substitutes. Operators in thepolymerization field therefore do not consider that the polymerizationof a class of monomers has been sufficiently developed unless methodshave been devised by which the monomers may be polymerized to thenormally solid or form-stable products.

Practically all of the work which has been done in connection with thepolymerization of vinyl ethers, excepting vinyl isobutyl ether, has ledto the formation of Viscous, sticky, honey-like masses. It appears tohave been the impression of the workers in this field that the vinylethers could only be effectively polymerized by causing the reaction totake place at such a violent rate that the reaction is completedimmediately after contact with the monomer of the usually employedacid-reacting catalyst. As a consequence, the prior art whenpolymerizing monomers other than the vinyl isobutyl ether utilizetemperatures ranging upwards from about C. and preferably within therange of 40 to 60 C., thereby obtain-ing only viscous,liquid-to-soft-solid products. For instance, U. S. P. 2,104,000 statesthat the temperatures to be employed for the polymerization of vinylethers should be generally from 10 to 120 C. and preferably between and100 C. It points out that where polymerization is effected by theutilization of a boron halide addition product, a temperature of between40 and 60 C. is to be recommended. One need only refer to the examplesof this patent-for instance, to Example 1, to observe that by operatinginthe manner proposed, the

atent products which are obtained are not form-stable but, on thecontrary, are viscous liquid products.

Vinyl isopropyl ether polymerizes under the usual conditions ofpolymerization with explosive violence, yielding only the sticky,viscous products of the prior art. This is true even working at reducedtemperatures, i. e., below 10" C., since reduction of temperature alonefails to abate the explosive nature of the reaction.

Vinyl n-butyl ether Was polymerized according to the prior art,utilizing temperatures ranging upward from about 10" C., and preferablywithin the range of 40 to 60 C. By these methods, the polymer obtainedis in every case a viscous, sticky, honey-like mass.

Vinyl methyl ether, polymerized by the process of U. S. P. 2,104,000, ata temperature of about 10 C. and above, is neither a crystalline norform-stable rubberlike polymer, but ranges from liquid to semi-solid,lacking the physical properties of a substitute for rubber.

I have found that vinyl ethers can be polymerized to rubberlike,form-stable polymers which are tough, resilient and generally non-tackysolids, and which, as distinguished from the products heretofore known,exhibit microcrystalline structure in that they yield X-ray fiberdiagrams in stretched condition.

Alkyl vinyl ethers yielding such polymers are especially the lower alkylvinyl ethers-namely, methyl vinyl ether, ethyl vinyl ether, propyl vinylether, isopropyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether,and secondary and tertiary butyl vinyl ethers.

It is an object of this invention to provide polymers of the aforesaidvinyl ethers, having the aforesaid novel properties.

In general, such products are obtained by carrying out thepolymerization in an appropriate solvent, such as a liquefied normallygaseous aliphatic hydrocarbon, or a hydrogen-containing halogenatedalkane, at temperatures below 30 C. and generally above 100 C.,especially from 40 to C. and preferably between 60 and 70 C., andadmixing the polymerization catalyst and the monomer progressively at aslow rate, and in appropriate cases, with suificient dilution, to insurea mild rate of reaction rather than a violent rate as employed in theprior art.

Catalysts employed for preparing the polymers of this invention areacid-reacting condensing agents such as tin tetrachloride, stannouschloride, aluminum chloride, gallium trichloride, ferric chloride, zincchloride, boron trifluoride, sulfuric acid, hydrochloric acid, or sulfurdioxide. For best results, the use of boron trifluoride or its additionproduct with organic oxygen-bearing compounds such as ethers, moreparticularly, the addition products of the dialkyl ethers such as borontrifluoride dietbyl ether and boron trifluoride dibutyl ether arerecommended. Other ethers suitable for such addition products aredipropyl ether, diamyl ether and ethyl methyl ether. The catalysts areused in relatively small amounts, for instance, in the proportionsreferred to in U. S. P. 2,104,000, and generally between 0.001% and 10%by weight, or preferably 0.08 to 5%, by weight of the vinyl alkyl ether.

Dilution of the catalyst, if normally solid or liquid, may be efiectedby using a solvent or diluent miscible with the catalyst. If thecatalyst is employed in the gaseous state, e. g. boron trifluoride,dilution can be effected by mixing with nitrogen. Liquid solvents ordiluents for this purpose may be aliphatic hydrocarbons such as liquidethylene or propane, or in the case of boron trifluoride ethercomplexes, the complex-forming ether. For example, for polymerizingvinyl isopropyl ether, a dilution of one part to /4 to 4 parts ofdiluent is suitable.

Various methods may be employed to attain and maintion the necessaryreaction temperature. Solid carbon dioxide, for instance, may be used toeffect this result. Similarly, the desired low temperature may besecured by the use of liquid refrigerants such as liquefied ethylene,methyl chloride and the like, refrigeration being effected bycirculation of the diluent or by evaporation of the diluent from thereaction mixture.

Solvents or diluents for the vinyl alkyl ethers include liquidhydrocarbons such as liquid ethane, propane, butane or ethylene.Hydrogen-containing halogenated alkanes which can be employed includemethyl chloride, methylene chloride, chloroform,monochlorodifluoromethane, ethyl chloride, ethylene dichloride,ethylidene dichloride and the like. Other hydrogen-containinghalogenated alkanes can be employed in the process of the invention,especially those having freezing points below -30 C. Particularlyvaluable results are obtained when hydrogen-containing chlorinatedalkanes of one to two carbon atoms are used. The quantity ofhydrogen-containing halogenated alkane employed as the diluent can bevaried over a wide range. In general, higher yields of polymer areobtained when from 1 to 5 mols of hydrogen-containing halogenated alkaneper mol of vinyl ether are employed. Larger amounts of diluent can beused but at a sacrifice in economy due to the cost of recovery of thediluent.

The hydrogen-containing halogenated alkane diluents may be used inadmixture with other suitable diluents, for example, liquid orliquefiable hydrocarbons, e. g. ethane, propane, butane, toluene,m-xylene, saturated ethers, e. g., methyl ether, ethyl ether, butylmethyl ether, butyl ethyl ether and the like. The use of mixtures ofdiluents is particularly desirable when the hydrogen-containinghalogenated alkane employed freezes at temperatures above that employedfor the polymerization of the vinyl ether. Mixtures of diluents in whichthe polymer is insoluble can advantageously be used to effect theprecipitation of the polymer as formed from the solution as illustratedin Example 2.

The reaction is carried out by adding the catalyst, cooled to thedesired reaction temperature, to the monomer or its solution, bothsimilarly cooled, or by adding the monomer, cooled to the reactiontemperature, to the catalyst mixture, which is likewise so cooled. Whilecooling the catalyst facilitates the reaction, the temperature thereofshould not be lowered to the reaction temperature if the catalystsolidifies at such temperature. In that event, cooling will be effectedto the lowest point where the catalyst still remains in the liquidstate. It can be readily ascertained, either from the critical tables orby simple experiments, to what extent the catalyst may be cooled withoutsolidification thereof taking place.

While good results are obtained by operating as stated, I have foundthat the reaction is expedited from the standpoint of heat control andspeed of the reaction and that products of a superior homogeneity areobtained if the catalyst and monomer be uniformly mixed at a temperatureat which polymerization does not ensure and polymerization effectedafter mixing by subjecting the mixture to a higher temperature andwithin the limits stated above. It is known that catalytic reactions arebest effected where steps are taken to insure the greatest possibleamount of contact between the catalyst and the substances which arebeing subjected to the reaction. By uniformly premixing the catalyst andthe monomer, such contact is produced.

The rate of reaction for each vinyl ether varies with the temperatureand for each there is a temperature below which the rate of reaction issubstantially zero when using an acid-reacting catalyst with an inertdiluent. For vinyl n-butyl ether monomer, such temperature is below -l00C. and it can be obtained by utilizing liquid ethylene as the coolingmedium. For the vinyl isopropyl ether monomer, such temperature is below-110 C., a temperature which can be obtained by employing liquidnitrogen, liquid methane or the like as the cooling medium. If desired,the catalyst can be added to the mixture of vinyl ether monomer and ahydrogen-containing halogenated alkane gradually and in small amountswith continuous stirring while maintaining the temperature above 70 C.By so controlling the conditions of the reaction, a smooth and even rateof reaction is obtained which is conducive to the maintenance of thenecessary low reaction temperatures. The catalyst should be addeddropwise to avoid local overheating and the danger of losing control ofthe reaction.

It is desirable to conduct the polymerization in the essential absenceof oxygen, that is, in the atmosphere of an inert gas such as nitrogenor carbon dioxide, the latter being conveniently provided by theaddition of solid carbon dioxide to the reaction mixture, followed byventing for removal of air.

Completion of the reaction may be determined by the absence of heatingor discoloration in a sample of the reaction mixture to which a smallportion of the catalyst has been added. Where the addition compounds ororganic oxygen-bearing compounds with boron fluoride are used, it isrecommended that they be drawn from such as have been distilled undervacuum and freshly made or stored under refrigeration as such measuresinsure greater retention of their catalytic activity.

When the reaction is complete, the catalyst is deactivated, a procedurewhich will hereinafter be referred to as quenching, by a treatment whichis preferably carried out at very low temperatures specifically withinthe limits at which the reaction has been effected. For effecting thequenching, use may be made of an alkali, such as ammonium hydroxide,sodium hydroxide, potassium hydroxide, an organic amine such asmethylamine, dimethylamine, ethanolamine, diethanolamine, pyridine andthe like, an alcohol such as methanol, ethanol, butanol, benzyl alcoholand the like, a carbonyl compound such as acetone, methyl ethyl ketone,formaldehyde, acetaldehyde and the like. Should it transpire that any ofthese quenching agents freezes at the quenching temperature,solidification of the same is avoided by employing with the quenchingagent a small amount of an inert diluent such as pentane.

The inactivated catalyst and quenching agent may be removed by washingthe solution of the polymer in its reaction solvent or in anothersolvent such as benzene at room temperature (about 20 C.) with water orwith water rendered alkaline by the addition of a small amount of analkali such as ammonia, sodium hydroxide, potassium hydroxide andthelike. On the other hand, such agents may be removed by dissolving thedry polymer in a solvent therefor and precipitating the polymer from itssolution with the-aid of a substance in which the polymer is insoluble,such as ethanol, methanol and the like. By causing the quenching to takeplace at the stated low temperatures, it is insured that there will beno conversion of any residual monomer at a temperature at which theundesirable low molecular weight products are formed.

Thevinyl ether employed in the polymerization may be that obtained fromthe reaction of acetylene and an alcohol. In such case it is necessaryto free it from the residual alcohol and any aldehyde and otherimpurities by washing with Water and then drying by allowing it to standover sodium or powdered potassium hydroxide for about 24 hours andfinally fractionally distilling it from the solid treating agent. Oneprecise fractional distillation is generally suflicient.

The rubbery, form-stable polymer of vinyl methyl ether of my inventionis soluble in aromatic hydrocarbons, chlorinated hydrocarbons, alcohols,ketones, ethers and esters, for example, in benzene, chlorobenzene,methanol, ethanol, acetone, dioxanere'thyl ether, ethyl acetate, e,tc.,and in water at temperatures below about 35 C.

The polyvinyl isopropyl ethers of the invention are spongy, elastic,tenacious solids, form-stable on storage, in contrast to previouslyprepared polyvinyl isopropyl ethers. They show substantially reversibleextensibility similar to partially vulcanized rubber. They arethermoplastic materials soluble in aromatic hydrocarbons such as benzeneand toluene, in ethers such as diethyl ether and the like, ketones suchas methyl isobutyl ketone and the like, and chlorinated hydrocarbonssuch as methylene chloride, carbon tetrachloride and the like. They areinsoluble in Water and the lower molecular weight alcohols such asmethanol, but are soluble in normally liquid higher molecular weightalcohols such as butanol, amyl alcohol, hexyl alcohol and the like.

The poyvinyl n-butyl ethers of the invention are likewise spongy,elastic and tenacious solids in contrast to polyvinyl n-butyl ethersobtained according to the prior art. They also show substantiallyreversible extensibility similar to partially vulcanized rubber.Although they are not sticky to the touch, they exhibit tack whenbrought into pressure contact with other surfaces. They arethermoplastic materials soluble in benzene, toluene, ethers, ketones,chlorinated hydrocarbons and the like. They are, however, insoluble inwater and the lower alcohols, although soluble in the higher alcohols,such as butanol and the like.

In general, because of the peculiar characteristics of the products,they may be put to use in many different fields. For instance, they maybe worked on a rubber mill for compounding purposes or cast from asolution thereof for laminating and coating purposes, and for theproduction of transparent sheets and foils. They may be extruded,pressure cast or molded. They may be used as adhesives, electricalinsulators, heat insulators, paint binders, wrapping films, containercoatings, and the like. Because of the many fields to which they areapplicable, these new products fill a substantial void in the polymerart.

The invention is illustrated by the following examples, although it isto be understood that my invention is not limited thereto. Parts are byweight unless otherwise specified.

Example 1 A reactor fitted with a stirrer, thermometer, means for addingthe catalyst and a vent, was cooled in a solid carbon dioxide-methanolbath and 20 parts of liquefied methyl vinyl ether and 80 parts ofmethylene chloride were added. To this mixture was added with stirring0.2 part of boron fluoride diethyl ether complex while maintaining themixture at 74 C. The temperature was then raised to and maintained at 70C. for 1 hour during which time polymerization occurred. A precooledmixture of 40 parts of methanol and 5 parts of concentrated ammoniumhydroxide was then added with stirring and the contents of the reactorallowed to come to room temperature. The insoluble inorganic productswere then removed by filtration, the methylene chloride evaporated andpolyvinyl methyl ether precipitated by the addition of water heated toabove 35 C. After drying, an excellent yield of transparent, colorless,tough, resilient, rubbery, form-stable polymer was obtained. X-rayexamination of the polymer gave a crystalline X-ray diffraction patternin contrast to a non-crystalline X-ray diffraction pattern for methylvinyl ether polymers prepared by the method of U. S. P.2,l04,000--2,l04,002.

Similar results are obtained when methyl chloride and ethyl chloride areused as the diluent in place of methylene chloride.

Example 2 A reactor similar to that described in Example 1 was cooled bymeans of a bath containing a mixture of solid carbon dioxide andmethanol. To this reactor were added 116 parts of liquefied methyl vinylether; 170.

6 parts of methylene chloride and 294 parts of liquefied propane. Duringa period of 40 minutes, 4 parts of boron fluoride-diethyl ether complexwere added to the stirred mixture at such a rate so as to maintain thetemperature within the range of --65 to -60 C. The polymer precipitatedas formed from the solution in the form of a white solid mass. When thepolymerization was complete, a precooled mixture of parts of methanoland 60 parts of concentrated ammonium hydroxide was added with stirringand the polymer separated. Essentially, a quantitative yield ofnon-sticky, chlorine free, form-stable, rubbery polyvinyl methyl etherwas obtained.

Example 3 Using the procedure as described in Example 1, except that 80parts of monochlorodifluoromethane were used in place of methylenechloride, a good yield of tough, resilient, non-tacky, form-stable,rubbery polyvinyl methyl ether was obtained.

If chlorodifiuoromethane or carbon tetrachloride is used as the diluentunder similar conditions, only a trace of low molecular weight, stickypolymer is obtained.

Example 4 A reactor similar to that described in Example 1 was cooled bymeans of a liquid nitrogen bath and 36 parts of vinyl ethyl ether, 43parts of methylene chloride and 102 parts of liquefied propane wereadded. To this mixture was added slowly with stirring 0.25 part of boronfluoride-diethyl ether complex. The'temperature of the mixture was thenincreased to 70 C. and maintainedwithin the range of 70 to 65 C. for 1hour. Ten parts of precooled concentrated ammonium hydroxide were thenadded with stirring and the solid phase separated and dried undervacuum. There was thus obtained a tough, granular, rubbery, form-stablevinyl ethyl ether polymer.

Example 5 750 parts by weight of liquefied propane and parts by weightof vinyl isopropyl ether were added to 1100 parts by weight of powderedsolid carbon dioxide confined in an air-tight apparatus. This mixturewas stirred for about /2 hour to replace all the air by carbon dioxide.A cooling bath of solid carbon dioxide in ethanol was used to surroundthe reactor for the purpose of maintaining the desired reactiontemperature, which is 78 C. Diethyl ether-boron fluoride boiling at 56C. at 25 millimeters pressure and diluted with diethyl ether in theratio of 2 parts of the catalyst to 1 part of the ether, was addeddropwise at such a rate that the aforesaid temperature of 78 C. was notexceeded.

The catalyst was added until no monomer remained. This point may bedetermined by removing a liquid sample from the apparatus, allowing itto warm to evaporate the volatile solvent and adding a small amount ofthe catalyst to the sample. If no polymerization ensues, as shown byheat evolution and charting under these drastic conditions, it isconcluded that the monomer has been completely polymerized.

Concentrated aqueous ammonia, cooled to the reaction temperature, wasthen added as a quenching agent. On warming to room temperature anddrying, a tough, spongy, rubberlike product was obtained which consistedof uniform granules which were non-sticky and formstable.

The intrinsic viscosity of the material was 20 (0.2% in benzene).

Example 6 The procedure was the same as in Example 5, except that theprecipitated polymer was removed as formed, by periodic interruption ofthe catalyst addition and by dippingout the solid polymer. The coldpolymer was washed with precooled ammonia hydroxide before warming anddrying.

Example 7 The procedure was the same as in Example 5, except ing thatthe catalyst was precooled before addition to the monomer by passing thecatalyst through a jacketed chamber cooled by a mixture of an alcoholand solid carbon dioxide.

Example 8 25 parts of powdered solid carbon dioxide, 50 parts ofliquefied propane, and parts of vinyl isopropyl ether were added to anopen flask. A stream of gas containing 50% boron trifluoride in nitrogenwas slowly; passed into the reaction mixture while stirring the same.The temperature, which was originally 78 C., rose to 70" C. A solid,rubberlike material wasprecipitated. The catalyst was quenched withaqueous ammonia and the product was freed of volatile material, washedwith methanol and dried.

Example 9 250 parts of liquefied butane and 50 parts of vinyl isopropylether were added to an open flask. This mixture was cooled to 78 C. byadding solid carbon dioxide to the mixture and by locating the flask inan external cooling bath of the same refrigerant. Precooled diethyletherboron fluoride which was diluted with diethyl ether in the ratio of3 parts of the boron fluoride addition product to 1 part of the diethylether, was added portionwise to the reaction mixture at such a rate thatthe temperaure was mainained between 78 C. and 72 C. At the completionof the reaction, quenching was effected With concentrated aqueousammonia and the mixture was thereupon warmed to room temperature. Ondrying, a rubbery, form-stable, slightly tacky solid was obtained.

Example 10 A diethyl ether-boron fluoride solution containing diethylether was added dropwise to a mixture of 50 parts of vinyl isopropylether, 400 parts of liquefied propane, and 500 parts of powdered solidcarbon dioxide. The reaction temperature was maintained at -78 to 75 C.by means of an outside cooling bath of solid carbon dioxide in ethanol.On quenching the reaction mixture with aqueous ammonia and drying, aslightly tacky, rubberlike solid was obtained. The polymer was dissolvedin benzene and precipitated with methanol to produce a product free ofcatalyst residue and of quenching agent. Upon washing with freshmethanol and drying, a formstable, spongy polymer was recovered.

Example 11 200 parts of vinyl isopropyl ether were added to 370 parts ofsolid carbon dioxide. A precooled solution (by volume) of diethylether-boron fluoride in diethyl ether was added dropwise to the reactionmixture while stirring. The reaction temperature was -78 to 77 C. Aftercompletion of the reaction, unchanged monomer was separated from thepolymer and recovered. The rubberlike polymer was quenched with aqueousammonia and dried. It was dissolved'in benzene and this solution waswashed several times with water to remove the catalyst residue andquenching agent. The polymer was recovered by evaporation of thebenzene, which may be reused in the process.

Example 12 ammonium hydroxide and the resulting mixture warmedto roomtemperature.

A rubberlike, form-stable product was thus obtained. r

Example 13 80.0' mls. of gaseous boron trifluoride were passed into 750parts of liquefied propane cooled externally by solid carbon dioxide toC. parts of vinyl isopropyl ether, precooled to --75 C., were slowlyadded portionwise to the mixture. After reaction was completed, themixture was quenched, whereupon there was obtained a spongy, elastic,form-stable polymer.

Example 14 A solution of 50 parts of vinyl isopropyl ether and 250 partsof methylene chloride was cooled to 78 C. with solid carbon dioxide.Precooled diethyl ether-boron fluoride diluted with diethyl ether in theratio of 2 parts of the boron fluoride complex to 1 part of the diethylether was added dropwise with stirring to effect the polymerization. Thecatalyst was inactivated with ammonium hydroxide. After warming to roomtemperature, methanol was added to precipitate the polymer from itsmethylene chloride solution and upon drying there was obtained atenacious, rubbery, form-stable product.

Example 15 Diethyl ether-boron fluoride diluted in the ratio of 3:1 withethyl ether was added dropwise to a solution of 50 parts of vinylisopropyl ether and 50 parts of vinyl n-butyl ether in 500 parts ofliquefied propane cooled to 78 C. The copolymer formed was treated withconcentrated aqueous ammonia at the temperature of the reaction. Ondrying, a rubberlike, form-stable copolymer was obtained.

Example 16 50 parts of vinyl isopropyl ether and 200 parts of liquefiedethylene were added to a reaction vessel located in a cooling batheffective to maintain a reaction temperature of --l00 C. Diluted ethylether-boron fluoride was added dropwise to the mixture while stirring tocause polymerization to ensue. A precooled aqueous ammoniamethanolsolution was employed to quench the reaction mixture. The mixture wasthen warmed to room temperature and the polymer dried. An elastic,form-stable product was thereby obtained.

Example 17 Dibutyl ether-boron fluoride boiling at 619 C. at 10 mm. anddiluted in the ratio of 2 parts to l with diethyl ether was addeddropwise to a solution of 50 parts of vinyl isoproply ether and 250parts of liquefied propane maintained at a reaction temperature of 45"C. with a cooling bath of solid carbon dioxide.

After the polymerization was'completed, a solution of sodium hydroxidein methanol was added as a quenching agent and the mixture was warmed toroom temperature. There was thus obtained a form-stable, granularpolymer having an intrinsic viscosity of 5 (1% in benzene).

Example 18 The polymerization was carried out as in Example 5, exceptthat in the place of solid carbon dioxide, a coil was fitted into thepolymerization apparatus through which liquefied ethylene was circulatedfor the purpose of maintaining the reaction temperature desired and foretfectively removing the heat of polymerization.

Example 19 The process was the same as in Example 5, except that insteadof using solid carbon dioxide as the refrigerant, the heat ofvaporization. of the solvent was utilized for this purpose. A vacuum of200 mm. was applied to the-reaction mixture containing liquid propane asthe solventto maintain atemperature of 75 C. The propane which wasrecoveredwascondensedand recycled to the reaction..-

9 Example '20 800 parts of liquefied propane were cooled by means of aliquid nitrogen bath to a temperature of 110 C., and 100 parts of vinylisopropyl ether were added to the liquefied propane. 3 mols of asolutions of 1 part of diethyl ether-boron fluoride in 3 parts ofdiethyl ether were then added. At the prevailing temperature, noappreciable polymerization of the vinyl ether took place.

The reaction mixture was then allowed to warm to a temperature of 78 C.,with vigorous agitation to cause polymerization to ensue. After thecompletion of the reaction, 10 mols of precooled 28% ammonium hydroxidewere added as a quenching agent and the mixture warmed to roomtemperature. A very homogeneous, rubberlike, form-stable product wasthus obtained.

Example 21 The procedure was the same as in Example 5, except that thediethyl ether-aluminum chloride complex was used in lieu of the diethylether-boron fluoride complex of Example 5.

Example 22 To 1100 parts of powdered solid carbon dioxide contained inanair-tight apparatus were added 750 parts of liquefied propane and 250parts of precooled vinyl n-butyl ether. A cooling bath of ethanol andsolid carbon dioxide was used to assist in maintaining the operatingtemperature, in this case 78 C. This mixture was stirred for about /2hour to vent out all air, which was replaced by an atmosphere of carbondioxide. Diethyl ether-boron fluoride, B. P. 56 C./25 mm., was addeddropwise at such a rate that the temperature was maintained essentiallyat -78 C. Insoluble polymer began to precipitate and the catalyst wasadded until no monomer remained. This point may be determined byremoving a sample of liquid, allowing it to warm up to evaporate thepropane from the monomer, and adding to this some catalyst. If nopolymerization is observed by heat evolution and charring, the test isconclusive of the fact that all the monomer has been polymerized.

Concentrated aqueous ammonia, cooled to below 50 C., was added as aquenching agent. On warming to room temperature and drying, a spongy,rubberlike, formstable polymer was obtained. It exhibited elasticity,re-

verisble extensibility and high tensile strength. After storage at roomtemperature for as long as nine months, the product retained itsgranular form and its form stability. The intrinsic viscosity of thismaterial was 11.0 (0.1% in benzene).

Example 23 it to flow through a chamber cooled by an alcohol-solidcarbon dioxide mixture.

Example 25 Into a flask were placed 200 parts of liquid butane and 50parts of vinyl n-butyl ether. The mixture was cooled to 78 C. by meansof solid carbon dioxide and an external cooling bath. Precooled diethylether-boron fluoride was added portionwise at such a rate that thetemperature was maintained between -77 and 78 C. At the completion ofthe reaction, quenching was eifected with concentrated aqueous ammoniaand the reaction mixture warmed to room temperature. On drying, apressure-tacky, form-stable product, rubbery in nature, was obtained.

Example 26 To 325 parts of powdered solid carbon dioxide were added 200parts of vinyl n-butyl ether. A precooled 25% solution (by volume) ofdiethyl ether-boron fluoride in diethyl ether was added dropwise withstirring. The reaction temperature was 7 6 to -77" C. After quenchingwith ammonia at this temperature and warming to room temperature, themixture was dissolved in benzene and precipitated with methanol toproduce a catalystfree product. On washing with fresh methanol anddrying, a form-stable, solid, rubberlike polymer was obtained.

Example 27 To a mixture of 600 parts of liquefied propane and 4 mols ofdiethyl ether-boron fluoride, maintained at 78 C. with the aid of solidcarbon dioxide and an external cooling bath, were added dropwise withstirring, 200 parts of vinyl n-butyl ether precooled to 76 C. Then 20mols of precooled 28% ammonium hydroxide were added and the contentswarmed to room temperature where the polymer, free of propane and carbondioxide, was dissolved in parts of benzene. This solution was added to2000 parts of rapidly stirred methanol. The precipitated polymer wasseparated, washed with 1000 parts of fresh methanol and dried to yielda. catalyst-free, rubberlike product.

Example 28 The polymerization vessel was charged with 5 0 pounds ofvinyl n-butyl ether and 200 pounds of liquefied propane. Solid carbondioxide was added to the mixture throughout the reaction to maintain atemperature of -78 C. to --74 C. Diethyl ether-boron fluoride was addedslowly to cause the polymerization to ensue.

At the completion of the catalyst addition, the mixture was warmed to 65C. to remove most of the carbon dioxide. Then a sodium hydroxidesolution was added to inactivate the catalyst. The vessel was closed andheated to about +5 C. The pressure rose to above 140 pounds per squareinch. With stirring, pounds of water were sprayed onto this warmedliquid propane solution of polymer. The stirring was stopped and thewater layer was separated. This water washing operation was repeateduntil all acidic material was removed. The washed polymer solution wasfreed of its propane by venting or by cooling and then filtering theliquid propane from the insoluble polymer. The solvent may be reused insubsequent polymerizations.

The product was dried at 40 to 50 C. at a vacuum of 20 inches for twelvehours to remove all moisture. A rubberlike, resilient, tenacious, highmolecular weight polymer was obtained.

Example 29 g A solution of 50 parts of vinyl n-butyl ether and 50 partsof methylene chloride was cooled to -78 C. with the aid of solid carbondioxide and an external cooling bath. Then at this temperature diethylether-boron fluoride was added dropwise with stirring to efliect thepolymerization. The catalyst was inactivated with concentrated aqueousammonia used as a quenching agent. After warming to room temperature,methanol was added to precipitate the polymer from solution, and atough, rubberlike product was obtained on drying.

Example 30 A solution of 100 parts of vinyl n-butyl ether and 100 partsof vinyl isobutyl ether in 800 parts of liquid propane was cooled to 78C. by means of solid carbon dioxide and an external cooling bath.Dibutyl etherboron fluoride, B. P. 61.9 C. at 10 mm., was added dropwiseto the solution. The polymer formed was treated at the reactiontemperature with concentrated aqueous ammonia as a quenching agent. Ondry1ng, a rubbery polymer was obtained.

Example 31 The polymerization was effected as in Example 22, except thatinstead of employing solid carbon dioxide as the cooling agent, the heatof vaporization of the solvent was utilized for this purpose. Byapplying a vacuum of 200 mm. to the reaction mixture, the temperaturewas maintained at 78 C. The propane which was removed was condensed andrecycled.

Example 32 then allowed to escape whereupon the pressure fell toatmospheric. thus obtained.

A form-stable, rubberlike product was Example 33 To a solution of 50parts of vinyl n-butyl ether and 200 parts of liquefied propane,maintained at 101 C. with the aid of a liquid ethylene bath, was addedslowly with vigorous stirring 2.5 mols of diethyl ether-boron fluoride.With continued agitation, the temperature of the reactants was raised to-75 C. where polymerization takes place as evidenced by precipitation ofpolymer. An alcohol-solid carbon dioxide bath surrounding the reactor issuitable for controlling the temperature at -75 C.

The contents of the flask were quenched with concentrated aqueousammonia while maintaining said low temperature. The reaction mixture wasthen warmed to room temperature at which the product was washed withmethanol and dried. There was thus obtained a formstable, veryhomogeneous, rubberlike' polymer.

Example 34 The process was the same as in Example 22, except that therewas employed the aluminum chloride-diethyl ether Apparently the vinylisobutyl ether has properties which distinguish it from the othermonomers in this field. According to the patent, for example, it isstated that at the temperatures given therein, immediate polymerizationensues when the monomer is contacted with the catalyst.

For instance, in Example 1, the polymerization, it is stated, commencesimmediately and turbulently and is practically complete after a fewseconds.

Polyvinyl isobutyl ether produced in this manner, however, does notyield an X-ray fiber diagram when stretched. As distinguished from thepolymers of the vinyl ethers of the prior art, the polymers of thisinvention are microcrystalline and yield X-ray fiber diagrams whenstretched. They are essentially produced by uniform and slowpolymerization which is absolutely essential to obtain uniformrubberlike, form-stable polymers.

The polymers of my invention are in properties and appearance similar torubber, being elastic, flexible and non-sticky, form-stable, highmolecular weight solids. They may exhibit tack when brought intopressure contact with other surfaces. They may be Worked on a mill forcompounding purposes, cast from solution for laminating and coatingpurposes and for the production of transparent sheets, may be extrudedor pressure molded, and employed as pressure adhesives. and electricalinsulators and for imparting strength and flexibility to waxes,paraflins and brittle plastic materials.

Variations and modifications of this invention will occur to personsskilled in the art and therefore I do not intend to be limited in thepatent granted, except as required by the prior art and the appendedclaims.

I claim:

1. A form-stable, elastic, rubberlike polymer consisting of apolymerized vinyl lower alkyl ether, said polymer being microcrystallineand yielding X-ray fibre diagrams in stretched condition.

2. A form-stable, elastic, rubberlike polymer consisting of apolymerized vinyl alkyl ether in which the alkyl group contains 1 to 4carbon atoms, said polymer being microcrystalline and yielding X-rayfibre diagrams in stretched condition.

'3. A form-stable, elastic, rubberlike polymer consisting of polymerizedvinyl methyl ether, said polymer being microcrystalline and yieldingX-ray fibre diagrams in stretched condition.

4. A form-stable, elastic, rubberlike polymer consistingof polymerizedvinyl isopropyl ether, said polymer being microcrystalline and yieldingX-ray fiber diagrams in stretched condition.

5. A form-stable, elastic, rubberlike polymer consisting of polymerizedvinyl n-butyl ether, said polymer being microcrystalline and yieldingX-ray fibre diagrams in stretched condition.

References Cited in the file of this patent UNITED STATES PATENTS2,061,934 Mueller-Cunradi et a1. Nov. 24, 1936 2,429,587 SchildknechtOct. 21', 1947 2,477,225 Zoss July 26, 1949 2,513,820 Schildknecht July4, 1950 2,555,179 Zoss May 29, 1951 2,609,364 Zoss Sept. 2, 19522,616,879 Zoss Nov. 4, 1952

1. A FORM-STABLE, ELASTIC, RUBBERLIKE POLYMER CONSISTING OF APOLYMERIZED VINYL LOWER ALKYL ETHER, SAID POLYMER BEING MICROCRYSTALLINEAND YIELDING X-RAY FIBRE DIAGRAMS IN STRETCHED CONDITION.